The present invention relates to a combiner for combining the optical apertures of three or more optical (which term includes electro-optical) systems. The invention also relates to optical systems including such combiner.
In many systems used for field observation and/or measurement, a simultaneous operation of several optical and electro-optical devices is required. An example of such a system is one including a thermal imaging sensor, a laser rangefinder, and a TV camera and optics, all simultaneously operating using separate spectral ranges of electromagnetic radiation.
Two methods are commonly used at the present time for the steering of the line of sight (LOS) of an optical or electro-optical device. One method involves mounting all the optical or electro-optical devices on a gimballed system and controlling the gimbals. A second method involves the use of a mirror as a steering device of the LOS. The latter method may involve mounting the optical and electro-optical devices side by side, with parallel optical axes, in which case the mirror must be large enough to include all the optical apertures; or may involve combining the optical apertures of the devices sequentially, using dichroic beam splitters. In the latter case, a common aperture may be used, but the length of the optical path and the individual field of view of each device may cause the common aperture to be very large.
In all of the known methods mentioned above, it is difficult to achieve compactness, which is very important in field observation and measurement, especially for vehicle mounted systems.
An object of the present invention is to provide a beam splitter single-element for combining at least three optical apertures in order to permit compactness of optical or electro-optical devices to be simultaneously operated. Another object of the present invention is to provide a system including the novel beam splitter and a plurality of optical or electro-optical devices simultaneously receiving or transmitting electromagnetic radiation therethrough.